Molecular and functional characterization of choline transporter in the human trophoblastic cell line JEG-3 cells

INTRODUCTION

Choline is essential for the synthesis of the major membrane phospholipid phosphatidylcholine (PC), the methyl donor betaine and the neurotransmitter acetylcholine (ACh), which is involved in several vital biological functions that play key roles in fetal development. In this study, we examined the molecular and functional characteristics of choline uptake in the human trophoblastic cell line JEG-3.

METHODS

We examined [(3)H]choline uptake in the human trophoblastic cell line JEG-3. The expression of CTL1 and CTL2 was evaluated by quantitative real-time PCR, western blotting and immunocytochemistry.

RESULTS

We demonstrated that JEG-3 cells take up [(3)H] choline by a saturable process that is mediated by a Na(+)-independent and pH-dependent transport system. The cells have two different [(3)H] choline transport systems, high- and low-affinity, with Km values of 28.4 ± 5.0 μM and 210.6 ± 55.1 μM, respectively. Cationic compounds and hemicholinium-3 (HC-3) inhibited choline uptake. Choline transporter-like protein 1 (CTL1) and CTL2 mRNA and protein were highly expressed in JEG-3 cells and were localized to the plasma membrane.

DISCUSSION

The present results suggest that choline is mainly transported via a high-affinity choline transport system (CTL1) and a low-affinity choline transport system (CTL2) in human trophoblastic JEG-3 cells. These transporters play an important role in the growth of the fetus.

Methyl-4-phenylpyridinium (MPP(+))-evoked dopamine release from rat striatal slices: possible roles of voltage-dependent calcium channels and reverse dopamine transport

We examined the properties of voltage-dependent Ca(2+) channels (VDCCs) mediating 1-methyl-4-phenylpyridinium (MPP(+))-evoked [3H]DA release from rat striatal slices. In some cases, the Ca(2+)-independent efflux of neurotransmitters is mediated by the high-affinity neurotransmitter-uptake systems. To determine whether such a mechanism might be involved in MPP(+)-evoked [3H]DA release. MPP(+) (1,10 and 100 microM) evoked the release of [3H]DA from rat striatal slices in a concentration-dependent manner. In the absence of Ca(2+), MPP(+) (10 and 100 microM)-evoked [3H]DA release was significantly decreased to approximately 50% of control (a physiological concentration of Ca(2+)). In the presence of Ca(2+), nomifensine (0.1,1 and 10 microM) dose-dependently and significantly inhibited the MPP(+)-evoked release of [3H]DA. Nomifensine (1 and 10 microM) also dose-dependently and significantly inhibited the MPP(+)-evoked release of [3H]DA under Ca(2+)-free conditions. MPP(+)-evoked [3H]DA release was partly inhibited by nicardipine (1 and 10 microM), an L-type Ca(2+) channel blocker. On the other hand, the N-type Ca(2+) channel blocker omega-conotoxin-GVIA (omega-CTx-GVIA) (1 and 3 microM) did not affect this release. omega-agatoxin-IVA (omega-Aga-IVA) at low concentrations (0.1 microM), which are sufficient to block P-type Ca(2+) channels alone, also had no effect. On the other hand, MPP(+)-evoked [3H]DA release was significantly decreased by high concentrations of omega-Aga-IVA (0.3 microM) that would inhibit Q-type Ca(2+) channels. In addition, application of the Q-type Ca(2+) channel blocker omega-conotoxin-MVIIC (omega-CTx-MVIIC) (0.3 and 1 microM) also significantly inhibited MPP(+)-evoked [3H]DA release. These results suggest that MPP(+)-evoked [3H]DA release from rat striatal slices is largely mediated by Q-type Ca(2+) channels, and the Ca(2+)-independent component is mediated by reversal of the DA transport system.

Pharmacological characterization and visualization of the glial serotonin transporter

Astrocytes contain transport systems that are capable of removing various neurotransmitters from the synaptic cleft by transporters present in the plasma membrane. Glial serotonin transporter (SERT) plays an important role in the re-uptake of 5-hydroxytryptamine (5-HT). We examined the pharmacological characterization of 5-HT uptake into rat cortical synaptosomes and cultured rat astrocytes, and the immunodetection of glial SERT proteins using specific site-directed monoclonal antibodies (MoAb). Furthermore, using a reverse transcriptase-polymerase chain reaction (RT-PCR) method, we addressed the expression of SERT mRNA in cultured rat astrocytes. We investigated the inhibitory effects of various monoamine uptake inhibitors on the uptake of [3H]5-HT into cultured astrocytes and cortical synaptosomes. Tricyclic antidepressants (clomipramine and imipramine) as well as selective serotonin re-uptake inhibitors (fluvoxamine, fluoxetine and zimelidine) were very potent inhibitors of [3H]5-HT uptake in both preparations. In contrast, the inhibitory effects of NE uptake inhibitors (nisoxetine and desipramine) and cocaine were weaker than those of 5-HT uptake inhibitors. In addition, dopamine (DA) uptake inhibitors (nomifensine and GBR-12935) exhibited a Ki value in the low micromolar range. The inhibitory potencies were in the order 5-HT uptake inhibitors (clomipramine, fluvoxamine, fluoxetine, imipramine and zimelidine) > NE uptake inhibitors (nisoxetine and desipramine) = cocaine > DA uptake inhibitors (nomifensine and GBR-12935). There was no difference in the order of the inhibitory effects of various monoamine uptake inhibitors between the two preparations. A correlation analysis of the potencies of various monoamine uptake inhibitors in the inhibition of [3H]5-HT into cultured astrocytes and cortical synaptosomes produced a highly significant correlation coefficient of 0.9893 (P < 0.0001). Immunocytochemical staining using anti-SERT MoAb in cultured astrocytes revealed that the plasma membrane, as well as intracellular, perinuclear compartments, presumably endoplasmic reticulum or golgi membranes, showed a considerable level of immunoreactivity. Extracts of astrocytes and synaptosomes from the cortex were immunoblotted with anti-SERT MoAb. SDS-PAGE/Western blots indicate that anti-SERT MoAb recognized two bands of 120 and 73 kDa in both preparations. RT-PCR demonstrated that astrocytes in cultured expressed mRNA for the cloned SERT protein, which has been characterized as the neuronal SERT. These pharmacological experiments indicate that this uptake process takes place through glial SERT that is very similar to neuronal SERT. Furthermore, the present data also indicate that the presence of the mRNA and protein for the neuronal SERT were established in cultured rat astrocytes, and the polypeptide portion of SERT in astrocytes and frontal cortex could be the same gene product.

Regulation of dopamine uptake by basic fibroblast growth factor and epidermal growth factor in cultured rat astrocytes

We examined the characteristics of dopamine (DA) uptake and its regulation by neurotrophic factors such as basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) in cultured rat astrocytes. In the presence of inhibitors of monoamine oxidase (MAO) and catechol-O-methyl-transferase (COMT), astrocytes took up DA by Na(+)-dependent and Na(+)-independent mechanisms that were sensitive to a reduction in temperature. The Na(+)-dependent and Na(+)-independent components increased linearly with increasing [3H]DA concentration (1-1000 microM), and showed no saturation. Na(+)-dependent DA uptake was significantly inhibited by ouabain, a Na(+)-K+ ATPase inhibitor. In bFGF-treated astrocytes, [3H]DA uptake increased in a time-dependent manner until 48 h, and declined after 72 h in both the presence and absence of Na+. In EGF-treated astrocytes, [3H]DA uptake increased in a time-dependent manner until 72 h in both the presence and absence of Na +. This enhancement of DA uptake induced by EGF or bFGF was significantly inhibited when the cells were cultured with actinomycin D, cycloheximide, or brefeldin A. Actinomycin D and brefeldin A also significantly inhibited the basal uptake of [3H]DA into astrocytes. These results suggest the existence of Na(+)-dependent and Na(+)-independent DA uptake in cultured rat astrocytes, and that EGF or bFGF might stimulate the expression and translocation of the extraneuronal DA transporter.

Pharmacological characterization of dopamine transport in cultured rat astrocytes

The effects of GBR-12909 (selective DA uptake inhibitor), zimelidine (selective 5-HT uptake inhibitor) and nisoxetine (selective NE uptake inhibitor) on the uptake of 30 nM [3H]DA into cultured rat astrocytes were examined. [3H]DA uptake was inhibited by approximately 50% by GBR-12909 or zimelidine in a concentration-dependent manner (100 nM to approximately 10 microM). Furthermore, the inhibition curves of GBR-12909 were biphasic, and uptake was completely inhibited by a high concentration of GBR-12909 (100 microM). [3H]DA uptake was also inhibited by approximately 50% by nisoxetine in a concentration-dependent manner (0.1 to approximately 100 nM), and nisoxetine was more potent than GBR-12909 or zimelidine. The inhibitory potencies were in the order nisoxetine > GBR-12909 > zimelidine. The uptake of [3H]DA under Na+-free conditions was approximately 50% of that under normal conditions. Thus, DA was taken up by both Na+-dependent and Na+-independent mechanisms. Nisoxetine (100 nM), zimelidine (100 microM) and GBR-12909 (10 microM) inhibited [3H]DA uptake into astrocytes only in the presence of Na+. On the other hand, this uptake was completely inhibited by a high concentration of GBR-12909 (100 microM) in the absence of Na+. The present data suggest that the Na+-dependent uptake of [3H]DA in cultured rat astrocytes may occur in the NE uptake system. Furthermore, astrocytes express the extraneuronal monoamine transporter (uptake2), which is an Na+-independent system, and this transporter is involved in the inactivation of centrally released DA.

Neurochemical characteristics and behavioral responses to psychological stress in ovariectomized rats

The present study was designed to clarify the time-dependent changes in brain monoamine turnover in the frontal cortex, hypothalamus, hippocampus, septum and amygdala after ovariectomy, and the difference in behavioral responses to psychological stress between sham-operated and ovariectomized (OVX) rats. At 2 and 4 weeks after ovariectomy, the turnover rates of dopamine and norepinephrine in all of the brain regions examined did not differ significantly between the sham-operated and OVX rats. However, 5-hydroxytryptamine (5-HT) turnover in all of the brain regions at 2 weeks after OVX was significantly lower than that in sham-operated rats. This difference was greater in the hypothalamus than in other brain regions. At 4 weeks after ovariectomy, 5-HT turnover in all of the brain regions examined was not significantly different between sham-operated and OVX rats. At 2 and 4 weeks after ovariectomy, exploratory behaviour (e.g., locomotor activity, head- dipping, crossing and rearing behaviours) in a non-stressed ovariectomy group did not differ from that in a non-stressed sham-operation group. Locomotor activity and the number of head-dips and crossings significantly (P<0.05) increased after repeated exposure to psychological stress for 5 days in sham-operated rats, but not in those at 2 weeks after OVX. At 4 weeks after ovariectomy, locomotor activity and the number of crossings and rearings in sham-operated and OVX rats were not significantly different in the psychological stress and non-stress groups. However, the number of head-dips significantly (P<0.05) increased with psychological stress in the sham-operated rats, but not in OVX rats. These results suggest that female gonadal hormones may play an important role in the regulation of brain 5-HTergic systems. These interactions between gonadal hormones and 5-HT metabolism may be related to 5-HT-related neuropsychiatric disorders.

Changes in urinary excretion of deoxypyridinoline in tail-suspended rats: effects of a bisphosphonate, YH529

Urinary excretion of deoxypyridinoline (D-Pyr) has been shown to be a useful marker for bone resorption. In this study, we investigated whether D-Pyr could be used to monitor the changes in bone resorption of the hind limb induced by tail-suspension. Male Wistar rats 5-weeks old were tail-suspended in a metabolic cage to unload the hind limbs. The control rats were not suspended. YH529 (YH), an inhibitor of bone resorption, or a vehicle (phosphate buffered saline=PBS) was administered daily starting 3 days before the commencement of tail-suspension. In the non-suspended rats receiving PBS, urinary excretion of D-Pyr did not show any significant change during the one-week experimental period. In the non-suspended rats receiving YH, D-Pyr excretion significantly decreased on day 5 and 7 when compared with that observed on day 0, in accordance with the systemic inhibition of bone resorption by YH. In the tail-suspended rats receiving PBS, D-Pyr excretion showed a tendency to increase on day 1, which is in agreement with our previous report that tail-suspension causes an early (on day 1 of suspension) and transient increase in bone-resorption of the hind limbs. In the tail-suspended rats treated with YH, the increase in D-Pyr excretion on day 1 was not observed, and a significantly lower excretion was noted from day 3 to 7 during the tail-suspension. It was suggested that D-Pyr excretion might reflect the transient increase in hind limb bone resorption induced by tail-suspension. As observed in-YH treated rats, D-Pyr excretion could serve as a good marker for the inhibition of systemic bone resorption.

Responses of trabecular and cortical bone turnover and bone mass and strength to bisphosphonate YH529 in ovariohysterectomized beagles with calcium restriction

Thirty-six beagles, 18 months of age, underwent ovariohysterectomy (OHX) or a sham operation. Sham-operated animals were given a diet with standard calcium (1.4%) (group 1, n = 6) or a restricted calcium diet (0.14%) (group 2, n = 6). The OHX animals were given the restricted calcium diet and YH529 orally with respective daily doses of 0, 0.02, 0.1, and 0.5 mg/kg of body weight (groups 3-6, n = 6 each) for 12 months. At the end of this period, the lumbar bone mineral densities (BMDs) in groups 2 and 3 and the load values for group 3 were significantly smaller than those for group 1. The midfemur BMD did not differ among the groups. The urinary deoxypyridinoline (U-Dpy) and bone formation rates (BFR/BS, BFR/BV) in groups 2 and 3 and the osteonal BFR/BS and trabecular osteoclast number (Oc.N/BS) in group 3 were significantly larger than the respective values for group 1. However, these parameters did not significantly differ between groups 2 and 3. The serum osteocalcin (OC) level, wall thickness (W.Th), and mineral apposition rate values for group 3 were significantly larger than those for group 2. In group 2, the trabecular activation frequency (Ac.F) increased by 3.11 times, and the percent values of the number of labeled osteons (L-Ot.N/T-Ot.N, %) in the tibia by 3.28 times over those for group 1. In group 3, the Ac.F increased by 3.20 times and the number of labeled osteons by 3.77 times over those for group 1. In groups 4-6, the U-Dpy and Oc.N/BS values were smaller, but their OC levels did not significantly differ from the level for group 3. The lumbar BMD, the load, and W.Th were dose-dependently significantly larger than those for group 3. The Ac.F values were significantly smaller, and the respective value in groups 4-6 was 67.9, 25.5, and 10.2% of that in group 3. The BMDs of the midfemur in groups 4-6 were significantly larger than those in group 3, but the ultimate load values did not significantly differ. The L-Ot.N/T-Ot.N values were also significantly smaller, and the respective value in groups 4-6 was 82.0, 48.5, and 55.2% of that in group 3. The tibial endocortical and periosteal BFR/BSs did not differ significantly. These data demonstrate that the effects of OHX on bone mass and turnover were small in the beagles fed a restricted calcium diet. YH529 maintained the mass and strength of the lumbar bone by reducing the bone resorption. The cortical bone appeared to be less sensitive to the agent than the trabecular bone in this animal model.

Effects of Toki-shakuyaku-san on electric footshock stress in ovariectomized mice

In the present study, ovariectomized mice were exposed to electric footshock stress for 7 days, and the duration of sodium pentobarbital-induced sleep was measured on the day following the last stress exposure. In ovariectomized mice, the duration of sodium pentobarbital-induced sleep before exposure to stress did not differ markedly from that in the sham-operation group. After exposure to stress, however, the duration of sodium pentobarbital-induced sleep in ovariectomized mice was shortened significantly, compared to the ovariectomized mice without stress. When the effect of Toki-shakuyaku-san on the stress-induced shortening of sleep time was studied, it was found that the shortening of the sleep time was suppressed by treatment with Toki-shakuyaku-san. In ovariectomized mice, the increase in hypothalamic noradrenaline (NA) turnover in response to stress was significantly greater than that in mice with intact ovaries. The stress-induced enhancement of NA turnover was suppressed significantly by Toki-shakuyaku-san in a dose-dependent manner, beginning with a low dose level. When effect of 17Beta-estradiol on the stress induced-shortening of sleep time was examined in ovariectomized mice, by high doses of 17Beta-estradiol the shortening of the sleep time was prolonged. A major difference between 17Beta-estradiol and Toki-shakuyaku-san was the marked uterine weight gain observed following 17Beta-estradiol treatment despite no effect of Toki-shakuyaku-san on uterine weight. The results in this study suggest that Toki-shakuyaku-san may reduce menopausal symptoms by a mechanism different from that of estrogen.

Protective effects of Hange-shashin-to on water-immersion restraint stress-induced gastric ulcers

Hange-shashin-to (HST) is a traditional Chinese herbal prescription (Banxia Xiexin Tang) which has long been used in the therapy of gastric functional disorders. In this report, the effect of HST extract on water-immersion restraint stress-induced gastric ulcer based on the changes in gastric mucin content and the variations of monoamine contents in hypothalamus were investigated. Ulcer index was microscopically measured by the sum total of the lengths of ulcers in glandular stomach. Gastric mucin content was determined by a PAS-staining methods and the monoamine contents were detected by HPLC-ECD method. HST extract was orally administered at 1, 2 and 3 g/kg for three consecutive days before stress exposure. Water-immersion restraint stress decreased the mucin content and produced gastric ulcers in a restraint time-dependent manner. Pretreatment with HST extract markedly inhibited the reduction of gastric mucin content and the development of gastric ulcer with significant differences (p < or = 0.01). The remarkable decrease of NE and 5-HT contents but prominent increases of MHPG and 5-HIAA contents were observed in hypothalamus after water-immersion restraint stress (p < or = 0.01). Those changes in monoamine contests in hypothalamus were also significantly inhibited by the pretreatment with HST extract at higher dosage (p < or = 0.05). These results indicate that the changes in gastric mucin content and the variation of monoamines in hypothalamus relate to the pathogenesis of water-immersion restraint stress-induced gastric ulcers, and it is suggested that the prophylactic effects of HST extract on stress induced gastric ulcers may be associated with an increase in gastric mucin content, although the prevention of HST extract on the extraordinary changes in monoamine contents in hypothalamus due to stress cannot be ruled out.

Administration of bisphosphonate prevents disuse bone atrophy induced by tail suspension

We recently demonstrated that osteopenia induced by rat tail-suspension was associated with an initial increase in bone resorption. To study the significance of the increase in early bone resorption for osteopenia, we investigated whether administration of YH529, a third-generation bisphosphonate, prevents the development of osteopenia as evidenced by increased wet weight of the femur, together with its calcium and phosphorus contents, when compared with those of tail-suspended rats treated with the vehicle alone. These results suggested that the initial increase in bone resorption plays an important role in the development of osteopenia induced by tail suspension.

Effect of bisphosphonate administration on the excretion of stress hormones in tail-suspended rats

We demonstrated that administration of a bisphosphonate, YH529, prevents the development of disuse atrophy of the hind limbs induced by tail-suspension in rats. Since tail suspension is accompanied by an increase in the secretion of stress hormones, we studied whether administration of bisphosphonate affects the secretion of stress hormones during that procedure. Tail suspension was carried out in a metabolic cage by connecting a wire inserted through tail bone to the ceiling of the cage. The control rat received the same treatment but was not suspended. YH529 or a vehicle (PBS=phosphate buffered saline) was administered daily starting 3 days before the commencement of tail suspension. Urine samples were collected before the wire was inserted (day 0), on the day of insertion (day 1) and 3, 5 and 7 days after. In the control rats receiving PBS, urinary excretion of corticosterone and epinephrine did not change throughout the 7-day experimental period. In the control rats receiving YH529, urinary excretion of corticosterone increased significantly on the day of tail-piercing and wiring but then returned to the prior level. This increase was not observed in the control group receiving PBS. In the tail suspended rats, excretion of corticosterone and epinephrine increased significantly in both PBS and YH529 groups, the highest level being observed on the first day of tail suspension. Although statistically not significant, corticosterone excretion on day 1 of tail suspension was higher in the YH529 groups than that in the PBS group. It is thus suggested that administration of YH529 causes an augmented response to stress load.

Effects of bisphosphonate on bone metabolism in tail-suspended rats

Our previous studies demonstrated that tail suspension causes early, transient increases in osteoclastic activity, followed by a decrease in osteoblastic activity in the hind limbs of rats. To assess whether this early increase in bone resorption is important in the development of disuse atrophy, the effect of YH529, a third generation bisphosphonate, was studied on hind limb atrophy in rats subjected to tail suspension. YH529 (YH group) or PBS (control group) were administered subcutaneously in 5-week-old male Wistar rats suspended for 7 days. In the control group, wet weight, calcium and phosphorus contents decreased significantly in the femur but they did not change in the humerus. In the YH group, however, these parameters did not change significantly in the femur, but both calcium and phosphorus increased significantly in the humerus. These results indicate that the inhibition of bone resorption by YH529 prevents the development of disuse atrophy induced by tail suspension. It is thus suggested that early increases in bone resorption are important for the development of disuse bone atrophy.

What is the difference of bone growth in SHR and SD rats?

1. Both sexes of spontaneously hypertensive rats (SHR) and Sprague-Dawley (SD) rats were used in this study. 2. At 6, 12, 18, 24, 30, 36, 42, 48, 54 and 60 weeks old, tibia length (L), volume (V), dry weight (DW), bone mineral density (BMD) in tibia and serum biochemical parameters (Ca2+, Ca, iP, ALP, TRAP) were measured. 3. At the 18 and 48 weeks old, bone morphometry was performed (mineral apposition rate, trabecular bone volume and trabecular thickness). Serum PTH and osteocalcin level were determined in 18 week old rats. 4. The time course change of DW, L and V were almost the same as the trends of bodyweight in each group, namely, male SD had the highest value, female SD and male SHR showed the same value and the lowest figures were obtained in female SHR. 5. BMD of the middle area showed almost the same trends with the time course change of bodyweight. On the other hand, both sexes of SHR had lower BMD than that of SD in the proximal area. 6. Serum biochemical parameters showed the same trends in both sexes of SD and SHR except for ALP (a marker of bone formation) which was higher in male than in female rats. 7. Mineral apposition rate, trabecular bone volume and trabecular thickness were not different between the same sex of SD and SHR. 8. These findings suggest that trabecular bone in SHR had a lower mineral status than that of SD rats not only in the adult but also in the young. This alteration may due to the abnormal mineralization mechanisms.

Effects of various dopamine uptake inhibitors on striatal extracellular dopamine levels and behaviours in rats

In vivo central effects of some dopamine uptake inhibitors were evaluated in both brain microdialysis and behavioural studies in rats, and compared with their in vitro affinities to dopamine uptake sites. IC50 values of GBR12909 (1-[2- bis(4-fluorophenyl)methoxy]ethyl]-4-(3- phenylpropyl)piperazine), diclofensine, mazindol, amfonelic acid and nomifensine for inhibiting 1 nM [3H]GBR12935 (1-[2-(diphenylmethoxy)ethyl]-4-(3-phenylpropyl)piperazine) binding to rat striatal membrane were 7.0, 36, 81, 187 and 290 nM, respectively. In the brain microdialysis study, dopamine levels in the striatal dialysates were increased to 16.3- (GBR12909), 14.1- (nomifensine), 4.8- (diclofensine) and 1.9-fold (amfonelic acid) the respective basal levels 40-60 min after i.p. administration (0.1 mmol/kg) and thereafter decreased slowly but remained at the elevated levels for a further 3 h, while mazindol gradually increased dopamine levels though less pronouncedly than others (1.7-fold 200 min after administration). Remarkable and comparable stereotyped behaviours (licking and forepaw treading) were continuously observed at least for 3 h after administration of GBR12909, nomifensine and amfonelic acid, while stereotypies induced by diclofensine and mazindol were moderate and marginal, respectively. In vivo potencies of dopamine uptake inhibitors to increase the extracellular dopamine levels in the striatum tended to correlate with their in vitro affinities to dopamine uptake sites except in the case of nomifensine, and correlated significantly with their potencies to induce stereotyped behaviours except in the case of amfonelic acid. Based on these findings, pharmacological characteristics of these dopamine uptake inhibitors are discussed.

Decreased mitogenic and osteogenic responsiveness of calvarial osteoblasts isolated from aged rats to basic fibroblast growth factor

Osteoporosis seen in aged individuals is represented by the reduced bone mass most likely resulting from decreased bone formation by osteoblasts. To examine whether aging causes a decrease in osteoblast activity, calvarial osteoblasts were isolated from aged rats (AOB) and studied for the capacity of the cells to form mineralized bone-like nodules in comparison with that of fetal calvarial osteoblasts (FOB). There were no significant differences in basal mineralized bone-like nodule formation determined by quantifying the size of the nodules which were formed in the cultures of AOB and FOB. However, the responsiveness of AOB to growth factors was profoundly reduced. AOB showed only marginal increase in mineralized bone-like nodule formation and growth in response to basic fibroblast growth factor (bFGF). On the other hand, bFGF markedly promoted mineralized bone-like nodule formation and proliferation in FOB. These results suggest that decreased responsiveness to local osteotropic growth factors such as bFGF might account for the reduced bone formation by aged osteoblasts, which in turn leads to the loss of bone mass characteristic for senile osteoporosis.

CPA enhances Ca2+ entry in cultured bovine pulmonary arterial endothelial cells in an IP3-independent manner

Studies of rat aorta revealed that cyclopiazonic acid (CPA), an inhibitor of the endoplasmic reticulum Ca2+ pump, released endothelium-derived relaxing factor (EDRF) and relaxed the muscle. We have used CPA to elucidate how this inhibitor of Ca2+ uptake into internal stores affects K+ channels and Ca2+ entrance in cultured bovine pulmonary endothelial cells using patch-clamp techniques. CPA increased a Ca(2+)-dependent outward K+ current for many minutes, presumably as a consequence of the unbalanced leakage of Ca2+ from internal stores and Ca2+ entrance across the cell membrane. An expected consequence of this activation of the outward current change is hyperpolarization of the cell membrane and increased driving force for Ca2+ entry. CPA activated the influx of extracellular Ca2+ through nonselective cation channels. Ca2+ influx through nonselective cation channels could help maintain intracellular Ca2+ concentration elevation and EDRF release. CPA also reduced the inwardly rectifying K+ current. Inositol 1,4,5-trisphosphate (IP3) in the patch pipette also produced an increase in outward K+ currents, which were Ca2+ dependent. After depletion of Ca2+ internal stores by CPA, the response to IP3 was abolished. Heparin in the patch pipette reduced the increase in outward currents induced by bradykinin, an agonist known to raise IP3 and to release Ca2+, but did not prevent CPA-induced increases in outward current. Thus CPA acts to elevate Ca(2+)-activated currents in endothelial cells by a mechanism independent of IP3-induced release, and this may lead to EDRF release both directly and as a consequence of Ca2+ entry through nonselective cation channels driven by an increased electrical gradient for Ca2+.

Contractile hyperreactivity and alteration of PKC activity in gastric fundus smooth muscle of diabetic rats

Contraction dose dependently induced in gastric smooth muscle of diabetic rats by Bay K 8644 in the presence of 20 mM KCl was about two times that induced in controls, and was inhibited more than 50% by 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7). Contraction was caused in diabetics but usually not in controls by 10(-5) M phorbol 12-myristate 13-acetate (PMA). In diabetics, this contraction was about 2.5 times that in controls. Protein kinase C (PKC) activity in the soluble fraction was depressed by H-7 or staurosporine, and depended on PMA concentration, but was greater in diabetics than in controls at any PMA concentration. PKC activity in the soluble fraction was inhibited by lower Ca2+ concentration, and was greater in diabetics than in controls. Affinity and density of binding sites of a Ca2+ channel antagonist ligand, [3H]PN200-110, were the same in plasma membrane-enriched fractions isolated from either controls or diabetic preparations. Thus, hyperreactivity in diabetic fundus may depend, in part, on alteration of PKC properties, but not on the density of Ca2+ channels.

Different mechanisms can activate Ca2+ entrance via cation currents in endothelial cells

Effects of Endothelin-1 (ET-1) and cyclopiazonic acid (CPA) on non-specific cation channels in cultured bovine pulmonary artery endothelial cells (BPAECs) were investigated using the patch-clamp technique. In a bath solution containing Ca2+ as a permeant cation, 10 nM ET-1 increased inward and outward currents and this current reversed at -10 mV instead of -60 mV. Under similar conditions, 10 microM CPA, an inhibitor of Ca2+ pumps in the sarcoplasmic reticulum, also increased both currents which now reversed near -10 mV. An inorganic Ca2+ influx blocker, La3+ at 50 microM completely blocked ET-1 and CPA-evoked currents restoring the reversal potential to -60 mV. ET-1 and CPA evoked currents were partially blocked by 50 microM SK&F 96365 (a putative inhibitor of receptor-mediated Ca2+ entry). ET-1 and CPA increased Ca2+ influx by activation of the Ca(2+)-permeable non-specific cation channels, which are gated by the depletion of intracellular Ca2+ stores in endothelial cells. These results, together with a previous study demonstrating that this Ca2+ entrance pathway can be opened directly by one vasodilator (LP-805) reveal that different mechanisms exist to activate Ca2+ entrance into endothelial cells. All may allow sustained release of endothelium-derived relaxing factor (EDRF).

Endothelin-1 inhibits inward rectifier potassium channels and activates nonspecific cation channels in cultured endothelial cells

A predominant inward rectifier and a small outward potassium current were obtained in whole-cell patch-clamp recordings from cultured bovine pulmonary arterial endothelial cells. Application of endothelial-1 (ET-1; 10-100 nmol/l) inhibited the inward rectifier. Washout with bath solution did not recover the current decreased by ET-1. In cell-attached studies, ET-1 (1 nmol/l) inhibited single-channel activity of the inward rectifier and in some patches enhanced activity of the outward potassium current without change of conductance. A non-specific cation current which is permeable to calcium was identified in cell-attached patches in cultured human umbilical vein endothelial cells. ET-1 (1 nmol/l) increased activity of the nonspecific cation channel. ET-1 may increase calcium influx into endothelial cells and promote synthase and release of endothelium-derived factors.

Cyclopiazonic acid stimulates Ca2+ influx through non-specific cation channels in endothelial cells

A non-specific cation channel in cultured human umbilical vein endothelial cells was obtained by cell-attached patch-clamp study. This channel showed a conductance of 28 pS when both pipette and bath contained 140 mM potassium chloride. when pipette solution was changed into 140 sodium chloride with 5 mM calcium chloride, the conductance was 26 pS. when 120 mM calcium chloride was used as the only cation in the pipette, a conductance of 6 pS was obtained. Bath application of cyclopiazonic acid, an inhibitor of the sarcoplasmic reticulum Ca2+ pump in smooth muscle and other tissues, dose dependently activates this non-specific cation channel. It is assumed that cyclopiazonic acid by blockade of the refilling of Ca2+ stores depletes the rapidly exchanging intracellular Ca2+ stores and this action stimulates Ca2+ influx through the non-specific cation channels in human umbilical vein endothelial cells.

Properties of the LP-805-induced potassium currents in cultured bovine pulmonary artery endothelial cells

The actions of 8-tert-butyl-6,7-dihydropyrolo[3,2-e]-5- methylpyrazolo[1,5-a]pyrimidine-3-carbonitrile (LP-805) on membrane K+ currents in cultured bovine pulmonary artery endothelial cells were investigated using the patch-clamp technique. In the whole-cell voltage clamp experiments, with 11 mM ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) in the pipette, membrane currents revealed only an inwardly rectifying K+ current, and no outward current could be observed at depolarized potentials. Using a pipette solution containing 0.3 mM EGTA, outward K+ current was present in response to depolarizing voltage steps from a holding potential of -60 mV. LP-805 (1-10 microM) significantly increased outward K+ currents in a concentration-dependent manner. The increase of this K+ current was inhibited by 5 mM tetraethylammonium and 5 mM tetrabutylammonium to a level less than the control. Partial recovery occurred on washout. However, the increase of outward K+ current by 10 microM LP-805 was unaffected by 5 mM 4-aminopyridine and 1 microM glibenclamide. LP-805 (1-10 microM) significantly decreased the inwardly rectifying K+ current in a concentration-dependent manner. In cell-attached patches, inward single K+ currents were recorded at negative membrane potentials, and single channel conductance was 23 +/- 2 pS (n = 5). No outward current could be observed at positive potentials. LP-805 (10 microM) inhibited the inwardly rectifying K+ currents. Thus LP-805 inhibits inwardly rectifying K+ currents but activates outward Ca(++)-dependent K+ currents in bovine pulmonary artery endothelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of LP-805, a releaser of endothelium-derived nitric oxide, on systemic vasodilatation in vivo

We have investigated relations between hypotensive responses to LP-805, a newly synthesized vasodilator, and the production of nitric oxide (NO), in anesthetized rats. LP-805 (0.1-0.5 mg/kg, i.v.) or acetylcholine (ACh) (0.3-3.0 micrograms/kg, i.v.) caused a dose-dependent transient decrease in diastolic blood pressure. The decrease induced by 0.3 mg/kg LP-805 (i.v.) was partially inhibited by pretreatment with NG-nitro-L-arginine (L-NNA), a specific inhibitor of endothelial NO synthase, but the responses to lower or higher doses of LP-805 (0.1 or 0.5 mg/kg, i.v.) were not affected. The dose-dependent decrease in diastolic blood pressure, caused by LP-805, was not affected by pretreatment with L- or D-arginine. The dose-dependent decrease in diastolic blood pressure caused by ACh was not affected by pretreatment with L-NNA or with L- or D-arginine. The hypotensive response to 20-min infusions of LP-805 (100 micrograms/kg per min) was significantly inhibited by pretreatment with L-NNA (10 mg/kg, i.v.). The half-recovery times (T 1/2) of LP-805 or ACh-induced depressor responses were shortened by pretreatment with L-NNA. They were prolonged by L-arginine, but not by D-arginine. This shortening, by L-NNA, of the half-recovery time after LP-805 or ACh was reversed by L-arginine, but not by D-arginine. The T 1/2 of the LP-805-induced hypotensive response was not affected by pretreatment with indomethacin (1 mg/kg, i.v.). In the presence of L-NNA (10 mg/kg, i.v.), the T 1/2 of the LP-805-induced hypotensive response was not affected by pretreatment with indomethacin.(ABSTRACT TRUNCATED AT 250 WORDS)

Transforming growth factor beta 1-induced cellular heterogeneity in the periosteum of rat parietal bones

We examined the osteogenesis process in transforming growth factor beta 1 (TGF-beta 1)-treated neonatal and adult rats, aiming to investigate the age difference in the effect of TGF-beta 1 on mesenchymal cell differentiation. Recombinant human (rh) TGF-beta 1 (20 and 200 ng) was injected onto the outer periostea of the right side of the parietal bone of each rat once a day for 1-12 days starting at the age of either 1 day or 12 weeks. On the day after the final injection, the calvaria was excised and evaluated histologically. In the neonates, the 12-day treatment with rhTGF-beta 1 increased the number of osteoprogenitor cells, resulting in intramembranous ossification. In the adult rats, rhTGF-beta 1 induced differentiation of chondrocytes. Cartilage masses were surrounded by mesenchymal cells, which would differentiate into chondrocytes. The cartilage matrix was partially calcified, with chondrocytes buried therein. In the calcified matrix, marrow cavities containing some multinuclear osteoclasts were formed. These findings indicate that rhTGF-beta 1 stimulated the differentiation of mesenchymal cells into chondrocytes and produced the cartilaginous matrix. rhTGF-beta 1 induced intramembranous ossification of the parietal bone in neonatal rats, and it induced enchondral ossification in adults. This result suggests that the different responses of mesenchymal cells in the periosteum to rhTGF-beta 1 may depend on the age of the animals used: namely, they may reflect the respective osteogenic stages of modeling and remodeling.

Carcinosarcoma of the skin: immunohistochemical and electron microscopic observations

A rapidly growing, hemorrhagic, exophytic tumor on the upper back of a 44-year-old male patient was investigated. Histological, immunohistochemical, and electron microscopic studies revealed both basal cell carcinoma-like and spindle cell sarcoma-like structures intermingled in the same tumor. Clinical consequences to this patient were mainly dependent on the sarcomatous element.

Morphological study of recombinant human transforming growth factor beta 1-induced intramembranous ossification in neonatal rat parietal bone

Recombinant human transforming growth factor beta 1 (rhu TGF beta 1) was injected singly or repeatedly for 3-12 days into the periosteum of the right side parietal bone of neonatal rats under the period of bone growth, and the time course of histological changes of the bone was observed by light and electron microscopy and by enzyme histochemistry. The repeated injections of rhu TGF beta 1 at 200 ng/day increased the thickness of the bone tissue on the treated side, which was about twice the nontreated side value after 12-day injections. On the dermal side, preosteoblasts in the periosteum increased in an early stage of treatment, and thereafter, differentiation into osteoblasts, increase of bone matrix, bone marrow cavity formation, and increase of osteoclasts within the bone marrow cavities were observed. Activation of osteoblasts on the dura mater side was also seen. The single injection of rhu TGF beta 1 at 200 ng resulted only in increased osteoprogenitor cell layers and bone matrix formation in an early stage, and the thickness of the osteoprogenitor cell layers and bone tissue at 12 days after single injection was comparable to the values on the nontreated side. At 1 microgram, however, the osteoblasts were activated, and the osteoprogenitor cell layers and bone matrix formation were markedly increased. At 12 days, the bone tissue thickness on the treated side was about twice the nontreated side value, as in the repeated treatment groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of eumelanogenic and pheomelanogenic melanosomes in the same normal human melanocyte

Ellipsoid and spheroid melanosomes similar to those found in the hair matrix melanocytes of eumelanic C57BL mice and pheomelanic Ay mice, respectively, have been shown to coexist in the same human melanocyte. The difference in the three-dimensional ultrastructure of these melanosomes of the human hair matrix melanocyte has been determined by high-voltage transmission electron microscopy using a goniometer. By energy-dispersive X-ray spectroscopy, sulfur, one of the main characteristic chemical properties of pheomelanin, is detected in a significant amount in each spheroid melanosome, but is absent in ellipsoid melanosomes. Furthermore, the internal structure of the spheroid melanosomes is dissolved by treatment with 0.5 N NaOH solution, whereas the ellipsoid melanosomes are not affected. We proposed that in normal human melanocytes pheo- and eumelanogenesis occurs in spheroid and ellipsoid melanosomes, respectively.

Equid herpesvirus 1 infection in mice

When the HH1 strain of equid herpesvirus 1 was intranasally inoculated to mice, the virus propagated in mouse lungs and the animals showed clinical signs such as ruffled fur, hunched posture, depression and body weight loss. Mice recovered from these signs by day 12 and cleared the virus from their lungs and produced antibody by 7th day after infection. These convalescent mice did not allow growth of the rechallenged virus. Athymic nude mice, however, failed to clear the virus from their lungs. Most of field isolates from aborted fetuses were propagated in murine lungs but attenuated strains originated from the HH1 were not.

LP-805, a releaser of endothelium-derived nitric oxide, activates an endothelial calcium permeable non-specific cation channel

The actions of LP-805, a releaser of endothelium-derived nitric oxide, on Ca2+ permeable non-specific cation channel in cultured bovine pulmonary artery endothelial cells (BPAECs) were investigated using patch-clamp technique. In Ca2+ saline bath solution, 10 microM LP-805 increased inward and outward currents. LP-805 evoked currents were reversibly blocked by 50 microM La3+, an inorganic Ca2+ influx blocker. In Ca2+ and Na+ free saline bath solution, 10 microM LP-805 did not evoke these currents, when 2 mM Ca2+ was then added to the bath the inward current increased. Furthermore, in the Na+ saline bath solution (Ca2+ free), 10 microM LP-805 increased similar inward and outward currents, which were blocked by 50 microM La3+. LP-805 evoked currents were carried by either Ca2+ or Na+. With the pipette solution containing 11 mM EGTA, 10 microM LP-805 activated the inward and outward currents. The increase of inward and outward currents by 10 microM LP-805 was inhibited by 1 mM Ni2+ but not by 1 microM nicardipine or 50 microM SKF 96365. In conclusion, LP-805 increases Ca2+ influx into vascular endothelial cells through Ca2+ permeable non-specific cation channels. This may explain the release of endothelium-derived nitric oxide in endothelial cells by LP-805.

Effects of LP-805, a new vasodilating agent, on cytosolic Ca2+ and contraction in vascular smooth muscle of rat aorta

1. LP-805 (0.1-10 microM) caused the reduction in norepinephrine (NE)-and serotonin (5-HT)-induced maximum response, a parallel shift of the concentration-response curve for prostaglandin F2 alpha (PGF2 alpha), in a concentration-dependent manner, but not K(+)-induced maximum response. 2. In Ca(2+)-free solution, LP-805 (0.1-10 microM) markedly inhibited the phasic contraction induced by 0.3 microM NE and the contraction induced by Ca2+ (0.1-2 mM) in the presence of 0.3 microM NE, in a concentration-dependent manner. Similar results were obtained in the presence of 5-HT (10 microM) or PGF2 alpha (10 microM). 3. In fura-2 loaded strips, ryanodine (10 microM) and LP-805 (10 microM) abolished 1 microM NE- and 30 microM 5-HT-induced phasic contractions, and inhibited the increase in cytosolic Ca2+ levels by both the agonists in the absence of external Ca2+, but had no influence on the following sustained contractions. 4. The effects of LP-805 on PGF2 alpha-induced Ca2+ transient and large sustained contraction were similar to those of ryanodine. 5. These results suggest that a vasodilatory effect of LP-805 might account for inhibiting the mobilization of external Ca2+ through receptor mediated passway and the Ca2+ release from a ryanodine sensitive Ca2+ store.

Effects of LP-805, a new vasodilating agent, on rat thoracic aorta

1. In canine coronary arteries, the contraction induced by prostaglandin F2 alpha (PGF2 alpha), but not by 65.9 mM K+, were relaxed by LP-805 (0.01-10 microM) in a concentration-dependent manner. 2. In rat thoracic aorta, LP-805 (0.1-10 microM) also relaxed the preparations contracted with norepinephrine (NE) and PGF2 alpha, but did not relax the contraction produced by 65.9 mM K+. 3. LP-805 (3-10 microM) inhibited the increase in cytosolic Ca2+ levels and contractions evoked by NE (1 microM) in the absence or presence of external Ca2+ in rat thoracic aorta. 4. LP-805 (0.1-10 microM) inhibited synthesis of IP3 induced by NE (0.3 microM) and cyclic AMP phosphodiesterase activity, and increased intracellular cyclic AMP levels in rat thoracic aorta. 5. These results suggest that a vasodilatory effect of LP-805 is due to inhibiting the increase in cytosolic Ca2+ levels via stimulation of various receptors, modulating second messenger synthesis.

Contractile responses and calcium mobilization in renal arteries of diabetic rats

The causes of diabetes-associated change of renal artery vasomotion have not been established. We investigated both contractile responses to KCl and norepinephrine (NE) in renal arteries of rats with streptozotocin-induced diabetes and age-matched controls and the effects on Ca2+ mobilization. Renal arteries from diabetics had greater maximum contractile responses to KCl and NE, but the threshold concentrations and EC50 values of KCl and NE were similar in controls and diabetics. The concentration-response for Bay K 8644, a dihydropyridine Ca2+ channel agonist in the presence of 20 mM KCl was significantly greater in diabetics than in controls. The maximum contractile responses to Ca2+ in the presence of 10(-6) M NE were significantly (P less than 0.05) greater in diabetics than in controls. The increased contractile response at low concentrations of Ca2+ (0.01-0.05 mM) was inhibited in both preparations by 10(-6) M nifedipine, but at high concentrations of Ca2+ (0.1-2.5 mM) the inhibition by nifedipine was significantly less in diabetics than in the controls. 45Ca2+ uptake had significantly greater resting levels in diabetics than in controls. The uptake of 45Ca2+ induced by 10(-5) M NE was significantly greater in diabetics than in controls, and 10(-7) M prazosin diminished both responses. The results suggest hyperreactivity of contractile responses to KCl or NE, and hyperpermeability of renal artery smooth muscle membrane to Ca2+ in streptozotocin-induced diabetics.

Therapeutic effects of leflunomide, a new antirheumatic drug, on glomerulonephritis induced by the antibasement membrane antibody in rats

Leflunomide is a new antirheumatic drug. It was evaluated, in comparison with azathioprine (AZA) and methylprednisolone acetate (MPA), for its therapeutic effects on the glomerulonephritis induced in rats by rabbit antiserum against the rat glomerular basement membrane. Its effect on body weight was also determined. Leflunomide (2 and 10 mg/kg/day, po), AZA (20 mg/kg/day, po), and MPA (2 mg/kg/day, sc) were administered for 28 days from 5 days after the intravenous injection of the rabbit antiserum. Leflunomide at both doses significantly decreased the urinary total protein, plasma total cholesterol, and plasma fibrinogen. On the other hand, neither AZA nor MPA affected the parameters except that they tended to reduce the urinary total protein. All three compounds decreased the plasma rat anti-rabbit IgG titer. Histologically, leflunomide at the high dose showed apparent therapeutic effects on the glomerulonephritis, as judged by light and electron microscopy and by immunofluorescence; the lesions were improved and deposits of rat IgG and C3 along the glomerular capillary wall decreased to a great extent. AZA and MPA exerted no therapeutic effects on the histological parameters except that MPA tended to reduce rat IgG and C3 deposits. Body weights increased favorably and slightly during leflunomide and AZA administration, respectively, but decreased during MPA treatment. Thus, leflunomide had more potent therapeutic effects on glomerulonephritis and less side effects than the already marketed drugs, suggesting that the compound is highly effective in improving immunologically mediated forms of glomerulonephritis, including membranous glomerulonephritis, at their early stages.

Sodium pump activity and contraction of renal artery from spontaneously hypertensive rats

We investigated the hypertensive changes in renal arteries isolated from 21-week-old spontaneously hypertensive rats (SHR), and from age-matched normotensive Wistar-Kyoto rats (WKY). The maximum contraction of renal arteries from SHR in response to norepinephrine (NE), serotonin (5-HT) and KCl was greater than that of arteries from WKY. The threshold and EC50 concentrations of NE, 5-HT and KCl were not significantly different between SHR and WKY. Contraction induced by removal of K+ was inhibited by 10(-8) M prazosin. Less than 10(-7) M NE in K(+)-free solution did not cause contraction. Addition of 5.9 mM KCl to K(+)-free solution in the presence of 10(-5) M NE induced relaxation, which was followed by contraction to about the same level as that before KCl addition. The duration of the K(+)-induced relaxation in SHR (22.4 +/- 0.9 min) was slightly, but significantly shorter than that in WKY (26.6 +/- 0.8 min) arteries. In K(+)-free solution with reduced Na+, the duration of the relaxation induced by KCl was shorter than that in the normal solution, for both SHR (13.8 +/- 0.3 min) and WKY (14.1 +/- 0.5 min). Such differences could be caused by increased influx and decreased efflux of Ca2+, which depend on the Na+ concentration and are related to the Na(+)-Ca2+ exchange. The results suggest that enhanced renal vascular reactivity in hypertension may depend on structural changes and increased Na+ pump activity.

Relations between contractile responses and beta-adrenoceptors in gastric fundus of diabetic rats

Contractile responses to norepinephrine (NE), and the population of beta-adrenoceptors, were determined in gastric fundus smooth muscle from rats with diabetes induced by streptozotocin (STZ), and age-matched controls. Relaxation and/or contraction of fundus strips of controls and diabetics were induced by 10(-5)M NE. Responses to NE were mainly relaxation in gastric fundus isolated from controls, and contraction in fundus isolated from diabetics. Contraction was blocked by 10(-8) M prazosin and relaxation was blocked by 10(-6) M propranolol. Relaxation by isoproterenol of contraction induced by 10(-6) M acetylcholine was significantly less in fundus from diabetics than in that from controls. The number of beta-adrenoceptors, measured with [125I] iodocyanopindolol as a ligand, was significantly less in gastric fundus membrane isolated from diabetics than in that from controls, but affinity was no different. The level of plasma catecholamine was higher in diabetics than in controls. Results suggest that depression of gastric fundus relaxation and increase of contraction by NE in diabetics could be due to fewer beta-adrenoceptor binding sites caused by down-regulation by higher catecholamine level in diabetic rats.

Effects of leflunomide on glomerulonephritis induced by antibasement membrane antibody in rats

Leflunomide (HWA 486, a novel isoxazol derivative), shown to have potent immunosuppressant and antiinflammatory effects, was evaluated for its inhibitory and therapeutic effects on the glomerulonephritis induced in rats by rabbit antiserum against rat glomerular basement membrane. Leflunomide was administered orally to rats at 0.5 and 2 mg/kg/day for 20 days from 2 days before injection of the rabbit antiserum and at 2 mg/kg/day for 14 days from 5 days after the antibody injection. The present study consisting of 2 experiments for inhibitory (I) and therapeutic (II) effects of leflunomide revealed the following effects at 2 mg/kg: in experiment I, significant decreases in (a) urinary total protein, (b) plasma total cholesterol and fibrinogen and (c) thymus weight, and decreased incidences of fibrin deposits in Bowman's space, adhesion of the glomerulus to Bowman's capsule and deposition of rat IgG and C3; and in experiment II, decreases in (a), (b) and (c), though smaller than in experiment I, and decreases deposition of rat C3. Thus, leflunomide had potent inhibitory and limited therapeutic effects on glomerulonephritis, suggesting that the compound is effective in inhibiting the onset and development of glomerulonephritis.

[Local irritancy study of cefpirome sulfate]

As a series of safety studies of cefpirome sulfate (CPR), its local irritancy was examined in rabbits after the following treatments: intracutaneous injection (single), application into the conjunctival sac of the eye (single), intramuscular injection (single, 7-day repeated), and intravenous injection (8-day repeated). In addition, the hemolysis test was carried out with human blood. When CPR was injected intracutaneously at a high concentration of 20%, its irritating effects were only equal to or slightly stronger than those of distilled water for injection and Na2SO4 solution. The same concentration of the compound applied into the conjunctival sac had little irritancy to the eye. In the single intramuscular administration experiment, muscular changes caused by 10% CPR were comparable to those by 0.75% acetic acid, slightly severer than those by physiological saline, and slighter than those by 6% acetic acid at 2 days after administration, but at 7 days, the changes were apparently slighter than those by 0.75% acetic acid. CPR is classified under Grade 3 according to the draft guidelines for local tolerability studies issued by the Ministry of Health and Welfare of Japan. The repeated intramuscular administration experiment showed the following results. Muscular changes caused by 10% CPR were comparable to those by physiological saline and slighter than those by 0.75% acetic acid, 5% cefotetan (CTT) and 20% cephalothin sodium (CET) at 2 days after the last administration. At 7 days, the changes were slightly severer than those by physiological saline, but slighter than those by the other control solutions. Microscopically, a tendency toward recovery was marked. In the vascular irritancy experiment, the 10% CPR group showed thrombus macroscopically on and after day 5 of dosing. Microscopy at the end of the 8-day administration period revealed thrombus and organized thrombus. In the 20% CET group, thrombogenesis was slighter than that in the 10% CPR group, while perivascular changes were severer. The changes caused by 5% CTT (thrombogenesis, perivascular changes) were somewhat severer than those by 10% CPR. In the hemolysis test, 10% CPR solution applied to fresh blood from adult men caused to hemolysis when determined by the macroscopic or spectrophotometric method.

[Acute toxicity study of cefpirome sulfate in mice and rats]

Acute toxicity of cefpirome sulfate (CPR) was examined in 6-week-old mice and rats and immature (5-day-old) rats. The LD50 values of CPR (mg/kg) were as follows: (1) mice: intravenous, 2420 (95% confidence limits, 2122-2758) for males and 2400 (2181-2640) for females; intraperitoneal, 3850 (3407-4351) for males and 4200 (3889-4536) for females; and oral, 16200 (14781-17755) for males and 18500 (17290-19795) for females. (2) 6-week-old rats: intravenous, 1900 (1784-2023) for males and 2080 (1953-2215) for females; intraperitoneal, 6550 (6179-6943) for males and 5800 (5311-6334) for females; subcutaneous, more than 10000 for both sexes; and oral, more than 8000 for both sexes. (3) 5-day-old rats: subcutaneous, between 1750 and 2500 for males and 2080 (1651-2621) for females. Major changes in general health conditions observed in 6-week-old mice and rats were decreased spontaneous activity, lying prone, tremor, respiratory changes (slow or deep respiration, gasping), clonic or clonic-tonic convulsions. In the 6-week-old rats dosed subcutaneously, vocalization, writhing and cutaneous changes at the injection site (dark reddening or blackening, swelling, exfoliation, depilation, induration) were also observed. In the 5-day-old rats dosed subcutaneously, the changes noted were slow respiration, writhing, cyanosis, and dark reddening and swelling of the skin at the injection site. After administration, transient depression of body weight gain or loss of body weight was observed in the mice and rats except the rats dosed orally. These changes disappeared at 7 days after administration at latest, and all surviving animals showed favorable body weight gain thereafter. Necropsies revealed hemorrhage under meninges in the brain in many of the mice and rats which died. Other findings included subcutaneous changes at the injection site in the 6-week-old and 5-day-old rats dosed subcutaneously (dark reddening, retention of dark red fluid, retention of red, white or dark red gelatinous material) and changes in the peritoneal cavity in the 6-week-old rats dosed intraperitoneally (red or dark red spots on the serous membrane, reddening of adipose tissues).

[Effects of cefpirome sulfate on male sexual development in rats]

Cefpirome sulfate (CPR) was administered subcutaneously at 200, 500, and 1000 mg/kg/day to male rats for 5 weeks from 6 through 40 days of age and examinations were made to determine whether the antibiotic caused any detrimental effects on male sexual development when administered to juvenile rats. Cefotetan (CTT) was given at 1000 mg/kg/day as a positive control. Incrustation occurred at the injection site during administration in all treated groups. The CPR groups had no compound related changes in fertility, spermatozoa, and reproductive organs, while the CTT group showed decreased testicular weight, abnormal fertility and spermatozoa, and atrophied germinal epithelium of seminiferous tubules, atrophied epididymis, and decreased number of spermatozoa. From the results of this investigation, it may be concluded that CPR had no effects on male sexual development when administered to juvenile rats.

Effects of antithrombin III on glomerulonephritis induced by antibasement membrane antibody in rats

Antithrombin III (AT III), a plasma inhibitor of coagulation factors, was evaluated for its inhibitory effects on the development of glomerulonephritis induced by antibasement membrane antibody in rats. AT III was administered intravenously at 250 and 1000 Units/kg to rats once a day for 14 days after intravenous injection of rabbit antiserum against the rat glomerular basement membrane. In the rat model, the high dose of AT III reduced the urinary total protein, plasma total cholesterol and plasma phospholipid, and tended to lower the incidence of fibrin deposits in Bowman's space, cell proliferation in the glomeruli, and PAS-positive granules (absorption droplets) in the glomerular epithelium. The above results suggest that AT III is effective in inhibiting the development of glomerulonephritis.

Melanogenic regulatory factors in coated vesicles from melanoma cells

Coated vesicles have been found to contain much higher tyrosinase and gamma-glutamyl transpeptidase activities than premelanosomes. This indicates that similar to tyrosinase, gamma-glutamyl transpeptidase, an enzyme responsible for pheomelanogenesis, is highly concentrated in coated vesicles after its maturation in Golgi associated endoplasmic reticulum (GERL). Furthermore, in the pre- and post-dopaquinone melanogenic pathway, coated vesicles convert dopachrome to colorless indole compounds more quickly than in premelanosomes because of their higher dopachrome conversion factor activity. Melanosomes have been found to exhibit indole conversion factor activity, while coated vesicles show indole blocking factor activity. In moderately tyrosinase-rich premelanosomes, the levels of dopachrome conversion factor and indole blocking factor are lower than in coated vesicles or melanosomes. High levels of indole blocking factor in coated vesicles may indicate why melanin polymer formation does not occur there in vivo despite their high tyrosinase activity.

Pharmacokinetic study of cefodizime in experimentally infected animals

Cefodizime, a new cephem antibiotic, was intravenously injected to mice with systemic or urinary tract infection by Escherichia coli and those with respiratory infection by Streptococcus pneumoniae, and the time courses of the plasma and tissue cefodizime levels were determined and compared with those in healthy mice (control group). In mice with systemic infection, the drug level in the plasma, liver, kidneys and lung changed on the basis of the two-compartment model. In this group, disappearance of the drug from plasma and tissues was obviously delayed and decrease in elimination constant (KE) and increase in the apparent volume of distribution (V2) were noted as compared with the control group. In the group with respiratory infection, T1/2(beta) and AUC for the hepatic drug level and T1/2(beta) for the renal drug level increased but in the other organs there was no great difference from the control group. In the urinary tract infection group, T1/2(beta) and AUC in the kidneys (infected site) and liver that mainly participate in elimination of cefodizime considerably increased differently from the control group. Changes of the distribution volume seemed to correspond with a physiological change of increase in body water content in the peripheral tissues (muscle, etc.) of the systemic infection group and in the liver, kidneys, etc. of the urinary tract infection group. Regarding the protein binding ratio, the urinary tract infection group showed a significant decrease as compared with the control group, but no distinct difference was noted in systemic and respiratory infections.

Calcium mobilization and phosphatidylinositol turnover in vas deferens smooth muscle of diabetic rats

The study concerned Ca2+ channels that are receptor-operated by norepinephrine (NE) and mediate hyper-reactivity of vas deferens smooth muscle from rats with streptozotocin (STZ)-induced diabetes, and the mediatory responses of these channels, such as tension development, Ca2+ uptake and phosphatidylinositol (PI) turnover. The contractile responses induced by adrenoceptor agonists were significantly greater in diabetic rat vas deferens than in the controls. A greater Ca2+ uptake was induced by 10(-5) M NE in strips from diabetic rats than in the controls. The uptake of Ca2+ was completely inhibited by 10(-6) M prazosin but not by 10(-5) M verapamil. Enhancement of Ca2+ release by 10(-5) M NE was faster and greater in diabetic muscles than in the controls. The accumulation of [3H]inositol phosphates was increased 4-fold in the controls and 7-fold in diabetic muscles by 10(-5) M NE. This increase was completely inhibited by 10(-6) M prazosin but not by 10(-6) M yohimbine. The data suggest that vas deferens smooth muscle hyper-reactivity in diabetic rats is due to increased PI turnover mediated by alpha 1-adrenoceptors, to the release of intracellular bound Ca2+ and to an increase of Ca2+ uptake through receptor-operated Ca2+ channels.